Machine gun safety device



Oct. 21, 1947.

GJW. GUNNER El AL MACHINE GUN SAFETY DEVICE Filedoct. 26, 1943 INVENTOR. 40 GEORGE W. GUNNER ROBERT J. BARTHOLOMEW 9 BY A TTOR NE Y Patented Oct. 21, 1947 MACHINE GUN SAFETY DEVICE George W. Gunner, Eggertsville, and Robert J. Bartholomew, Rochester, N. Y., assignors to Curtiss-Wright Corporation, a corporation of Delaware Application October 26, 1943, Serial No. 507,754

4 Claims.

1 This invention relates to a device for preventing uncontrolled firing of machine guns. More particularly, it relates to such a device wherein the breech bolt of the machine gun is held in a rearward position when it is desired not to fire the gun.

When a conventional machine gun is loaded and is ready for use under actual or simulated battle conditions, it is desirable to have it ready for instant operation at all times. In guns of the Browning type, this is normally accomplished by having a cartridge in the firing chamber whenever the gun is not actually being fired. The gun is fired by simply raising the rear end of a fulcrumed trigger bar (by means of a hand-operated or solenoid-operated trigger), and the gun continues to fire as long as the trigger bar is kept in position. Cartridges are actually fired only when the chamber is closed, 1. e., the breech bolt is in the forwardmost position.

The difiiculty with this method of operation is that, when the gun becomes overheated during firing, it is possible that the cartridge in the hot chamber will be exploded or discharged even when the trigger bar is in the inoperative (rear end lowered) position. This is known as uncontrolled firing due to cooking of the cartridge. Serious accidents may result from this.

It is therefore an object of this invention to provide a simple mechanical device, which may be used in combination with the conventional trigger mechanism in a machine gun, to prevent uncontrolled firing of a machine gun. It is another object to provide such a device which will hold the breech bolt of a machine gun in the rearmost position when the gun is not actually being fired (except before firing the first cartridge) Still another object is to provide means for permitting the chamber and barrel of a machine gun to be open between bursts of firing, thus furnishing an additional cooling effect. Other objects will appear hereinafter.

These objects are accomplished by means of a safety device known as the breech bolt hold-back device, and which may be more readily understood by reference to the accompanying drawings.

In the drawings, Figure 1 is a side view of a conventional machine gun of the Browning type, to which the novel hold-back device has been applied, the breech bolt being in the held-back position; Figure 2 is a side view, partly in elevation and partly in cross section, of a portion of Figure 1 on an enlarged scale; Figure 3 is a view taken along the line 3--3 of Figure 2; Figure 4 is a view taken along the line 4-4 of Figure 2; Figure 5 is a view taken along the line 5-5 of Figure 2; Figure 6 is a view corresponding to Figure 2, but with the breech bolt released and on its way forward; Figure 7 is a View corresponding to Figure 6 with the trigger bar in the active or firing position; Figure 8 is a view taken along the line 8-8 of Figure 7; Figure 9 is a perspective view showing the trigger mechanism according to the present invention; and Figure 10 is a fragmentary sectional View taken in a plane normal to the planes of Figures 2 and 3 showing a safety lock for the gun.

Referring now to the drawings, a conventional machine gun of the Browning type is indicated at [5 (Figure 1). In the form shown in the drawings, the gun is operated by a solenoid l6, whose plunger 2| moves forward in response to the impulse of an electric current. This plunger is normally held in the rearmost position (see Figures 2, 3, and 6) by means of a spring (not shown) when the current is turned ofl". Thus this form is particularly applicable to use where remote control is desired, such as in fighter aircraft. However, the invention is equally applicable to a gun operated by a direct hand-operated pusher.

The solenoid I6 is held in place on the buffer I! by means of extensions I8 and bolts l9. Part of the breech bolt mechanism of the gun is indicated generally at 20, and is shown in Figures 2 to 5 inclusive in its rearmost position, abutting against the buffer plate 26. Also in Figures 2, 3 and 6 inclusive, the trigger bar 22 is shown in its inactive or non-firing position.

The frame 34 of the breech bolt hold-back mechanism is fastened to the back plate 23 of the gun by means of bolts or screws 30. On this frame is fixed a pin 33, upon which two camsurfaced levers 3| and 32 are pivotally mounted or journalled, the cam surfaces of these levers to which reference is made being the surfaces engaged by the plunger 2|. The rear ends of these two levers are normally kept in the upward position (i. e., the levers are urged in the clockwise direction) by means of two springs 35 and 36 respectively, when the solenoid plunger 2| is in the inactive or rearmost position. These springs are mounted between a horizontally extending arm 31 of the frame 34 and the bottom surfaces of the levers 31 and 32.

The forward ends of the levers 31 and 32 pass through an opening 24 in the back plate 23 of the gun. The trigger of a gun not provided with the novel hold-back mechanism of this invention customarily passes through this opening, so that no modification of the back plate (other than mounting the bolts 39) is necessary in the practice of this invention. The lever 3 l in the position shown in Figures 2 and 3 is held in place by the coil spring 35. In this position it rests on the bottom edge of the opening 24, and is prevented from further movement in the clockwise direction bysuch bottom edge. Whenthe .breech bolt 20 is in the rearmost position (Figures 2-and 3), lever 3i catches a notched surface 25 of the breech bolt, and holds it in the rearmost position. Lever 32, in the position shown in Figures 2 and 3, is also prevented from further movement-in the clockwise direction by means of a stop 38. At the same time the trigger bar22is in the down or inactive position. Lever 32 is held inthepo sition shown in Figure 2 by means of a coil spring 36.

chamber.

Lever 32 is provided with a horizontally extending projection 39 adjacent its bottom edge. When the lever 32 is rotated in a counter-clockwisedirection by means of thesolenoidplunger 2 [against the action of spring 3 6, the top surface ofthis projection 39 is engagedbya leaf spring ill (see Figure 8 for the-activated position)-.and held in this position against theaction of the spring 36. .In this position an upwardly extending projection M at the forward end-of the lever 32'pushesupward against and actuate's the trigger bar "22.

r The operation of the device is asfollowsi' .When thefgun is to be prepared for usein actual. combat, the loading crew sets the device in the position shown in Figures 2 to 4, inclusive, of the drawings. In this position the breech bolt' 20. is held back by :the lever 3 l, and the trigger bar 22 is in the down or inactive position. To accomplish this, the loading crew releases lever 32by'pressing the leaf spring lEl outwardly (towards the right in Figure- 8 to arriveat the position shown in Figure 4) with the thumb. or'fingerfThe gun is loaded in the customary fashion, -thebreech bolt-being released by pressing down on the cam surface of the lever 3| with the thumb orfinger. In doing this it isimportant that'ithelever .32 .is

not actuated, since this will cause'the gunlto fire; I

The gun maybe prevented. fromfiringfdu'ring these operations by providing'an auxiliary safety mechanism orstop (not. shown) for. preventing upward'movement of the trigger bari22. For example, as shown in Figure 10, the gun may be provided with a turn 1ock'42which when turned to the position illustrated holdsthe trigger bar 22 in its lower or inactive position,. and which, when turned 90 degreesabout "pivot axis &3 from 'the position illustrated,,is disposed entirely to one side of'thebar 22 so thatthe. latter may be raised to-firing position. The position of the mechanism when the lever 3i is released, and the breech bolt is on the way forward, is indicated-in'Figure'fi. When the breech bolt is completely forward, the gun is loaded and ready-for firing, with a. cartridge in the chamber.

Whenit isdesired to fire the gunfor theTfirst time after loading, the solenoid i5. is actuated, causing the plunger 25 to move forward,- thus pushing downwardly on the cam surface'of levers 3| and 312, This position is shown in Figures '7 and -8of thedrawings. -Sinceflthe1bre'ech bolt is already in the forwardposition,lthismovement of the lever 3| has no efiect'on thebreech bolt. Movement of lever 32, hoWever,- including upward movement. of projection- @Lcauses the trigger bar 22 tomove upwardgthus firing the gun. Atthe same time, the-leaf gspring All will engage the projection 39,'so that henceforth the trigger bar 22 will remain in the active position, uninfiuenced by the solenoid plunger 2|. The gun will continue to fire as long as the solenoid plunger holds the lever 3| in the position shown in Figures 7 and 8.

When it is desired to cease firing, the electric current is shut off, releasingthesolenoid: plunger and returningit. to the rearmosti. position. Due to the action of the leaf spring 46, cartridges will continue to fire as long as the breech bolt is in the forward position and there is a cartridge in the -When the last shot is fired after releasing the solenoid, however, the lever 3| falls "into the notch 25. of the breech bolt 20 on its recoil 'strokepand; holds it in this position until it is desired'to-fire the gun again. Thus it is seen that, between bursts of firing, the chamber is emptyand'the breech bolt is held back, and uncontrolled firing of the gun is prevented. Since the chamber is open, cooling of the barrel and chamber isathus facilitated.

'Whenit is desired-tofire the guna'gain, the curfentis turned on, causing the-solenoid plunger 2! "to move forward as before. Thisv has no effect on thelever 32, since it is alreadyheld'in the active position by means of the leaf spring lll. Pressingdown onthe. cam surface r of lever: 3|, however, releases the breech bolt, causing a cartridge to be injected into-the chamber and the; gun to be fired immediately thereafter. Firing will continue as longas the lever 3 is-held inthis, position (see Figures and 8.)

"Eromthe above description-v anddrawings; it will beseen thatthere is provided a'simple and novel mechanism, which can. be incorporated in existing machine guns-without modification, and w hich willaccomplish. all the objects of the presentinvention. .In --addition,. particularly I when used in aircraft installations, an important advantage is due to the fact that the chamber is kept closed before firing the first. cartridge. Thus-,the gun is. protected from dust and. other debris during the take-off of airplanes or other periods ;of rough usage. 7

lt is obvious that many .changes: may-be made in the above described embodiment of the inven: tion without departing; from the spirit ithereof. For example, the breech bolt neednot be held.- in its rearmost: position, but-only sufficiently far to the-rear-thata .cartridgerisnotheld in thechamber. 'It. -is.-.underst0od that the invention 'is only toibe limitedas; defin'edin the appended claims.

-'-We claim:

1. In a machine gun of .thetype having a breech bolt movable between open and closed positions, a firing-"mechanism element movable between an active and can inactive .position; :and adaptedilto fire ionly' when theibreech bolt isin .closed:-posit-ion and thefiringi m'echanism: elementis in" active position: the c'ombination comprising a:first pivoted lever and-spring means for urging it into latching engagement with th breechbolt when the "latterisin-open --posit-ion, a second pivoted lever formovingthe firing mechanism element'to activeposition andspringimeans for resiliently holding 'saidsecond lever against such movement, a common actuating plunger for said levers'lf'or simultaneously swinging-them about their pivots againstathe resistance of their spring means to effect -movementof the firing element -to active position andto allow-the-breech bolt tomove free of the date-hing engagement :with the first lever, and*resi:lient..detent :means engageable with the second Llever .When ithe latter-:hast been ;so1moved for automatically holding the second lever and the firing mechanism element in active position.

2. In a machine gun of the type having a breech bolt movable between open and closed positions, a firing mechanism element movable between an active and an inactive position, and. adapted to fire only when the breech bolt is in closed position and the firing mechanism element is in active position: the combination comprising a first member having resilient means for urging it into latching engagement with the breech bolt when the latter is in open position, a second member for moving the firing mechanism element from inactive position to active position, a common actuator for said members for simultaneously n moving them to efiect movementof the firing element to active position and to allow the breech bolt to move free of the latching engagement with the first member, and detent means operable by and upon such movement of the second member for holding the firing mechanism element in active position.

3. In a machine gun of the type having a breech bolt movable between open and closed positions, a firing mechanism element movable between an active and an inactive position, and adapted to fire only when the breech bolt is in closed position and the firing mechanism element is in active position: the combination comprising a first member having resilient means for urging it into latching engagement with the breech bolt when the latter is in open position, a second member for moving the firing mechanism element to active position, a common actuator for said members for simultaneously moving them to effect movement of the firing element to active position and to allow the breech bolt to move free of the latching engagement with the first member, and detent means operable by and upon such movement of the second member for holding the second member and the firing mechanism element in active position.

4. In a machine gun of the type having a breech bolt movable between open and closed positions, a firing mechanism element movable between an active and inactive position, and adapted to fire only when the breech bolt is in closed position and the firing mechanism element is in active position: the combination comprising means for latching engagement with the breech bolt when the latter is in open position, means for moving the firing mechanism element to active position, a common actuator for the aforementioned means for simultaneously operating them to effect movement of the firing element to active position and to allow the breech bolt to move free of the latching means, and detent means automatically operable upon the first movement of the firing mechanism element to active position for holding the latter in said active position.

GEORGE W. GUNNER. ROBERT J. BARTHOLOMEW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,050,539 Moore et a1 Aug. 11, 1936 1,352,891 Green Sept. 14, 1920 1,286,884 Revelli Dec. 3, 1918 1,653,319 Studler Dec. 20, 1927 

